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GATE 2019 CS – Question 32

Engineering Mathematics · Probability and Statistics · 1 mark · Numerical answer

Two numbers are chosen independently and uniformly at random from the set $\{1,2,\dots,13\}$. The probability (rounded off to 3 decimal places) that their 4-bit (unsigned) binary representations have the same most significant bit is ________.

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Correct answer: 0.49 to 0.51

Explanation

The numbers 1 to 7 have MSB 0 (7 numbers) and 8 to 13 have MSB 1 (6 numbers). The probability is $\frac{7^2+6^2}{13^2}=\frac{85}{169}=0.503$.